1、INTERNATIONAL STANDARD INTERNATIONAL ORGANIZATION 0i7 STANOARDZATION .MEXYHAPOHAR oprAtiki3qWi no AHATAUAA.ROANSATION NTERNATIONALE DE NORMALISATON Steel - Determination of effective depth of hardening after flame or induction hardening Acier - D b) specifies the method for measuring this depth of h
2、ardening. 2 FIELD OF APPLICATION This International Standard applies to a) hardened layers with a depth greater than 0.3 mm; b) parts which, in the surface hardened condition, have at a distance 3 x DS from the surface, a hardness less than hardness limit (HV) - 100 Where these conditions are not sa
3、tisfied, the effective depth of hardness after flame or induction hardening shall be de- fined by agreement between the parties concerned. For steels where the hardness of a part at a distance 3 DS from the surface is above hardness limit (HV) - 100, the criterion may still be used on condition that
4、 a higher hard- ness limit is chosen for the assessment of the effective depth of hardening (see clause 3). 3 DEFINITION effective depth of hardening after flame or induction hard- ening (DS) : The distance between the surface of the prod- uct and the layer where the Vickers hardness (HV) under a lo
5、ad of 9,8 N (1 kgf)l ) is equal to the value specified by the term “hardness limit”.2) It is a function of the minimum surface hardness required for the part, given by the following equation : hardness limit (HV) = 0,80 x minimum surface hardness (HV) The effective depth of hardening after flame or
6、induction hardening is designated by the letters “DS”. This depth is expressed in millimetres, and is applicable to the area speci- fied in the drawing of the part, which may or may not have been ground depending upon the specification. 4 MEASUREMENT 4.1 Cases of dispute The method of measurement of
7、 the effective depth of hard- ening after flame or induction hardening specified in this clause shall be the only one applicable in cases of dispute. 4.2 Principle of the measurement The effective depth of hardening shall be determined from the gradient of hardness in a cross-section normal to the s
8、urface. It shall be estimated graphically on the curve rep- resenting the hardness as a function of the distance from the surface of the part. 4.3 Measuring procedure The measurement shall be carried out, unless otherwise agreed between the parties concerned, on a cross-section of the part in the ha
9、rdened condition. 4.3.1 Preparation of the surface to be examined The surface on which the measurement is to be made shall be polished so as to permit the correct measurement of the size of the hardness impressions. Every precaution shall be taken to avoid rounding the edges of this surface and over
10、- heating the part. 1) By agreement between the parties concerned, loads different from the reference load 9.8 N (1 kgf), within the range 5 to 50 N, may be used. By agreement between the parties concerned, the superficial Rockwell method for measuring the hardness may be used, in which case the har
11、d- ness limit value should be specified. 2) By agreement between the parties concerned, other values of the hardness limit may be used. The effective depth should then be desig nated by the use of a suffix to the letters “DS”. 1 Copyright International Organization for Standardization Provided by IH
12、S under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IS0 3754-1976 (El 4.3.2 Determination of the hardness The hardness impressions shall be placed along one or more parallel lines normal to the surface and within a band WV) I,5 mm in width (see
13、the figure). The distance between the surface and the successive im- pressions shall increase by steps of 0,l mm (for example d, -d,), the first point near the surface being 0,15 mm from the surface (d,). In the case of a large depth of sur- face hardening, the distance between the impressions may b
14、e greater, but the distance between the impressions shall remain 0,l mm in the immediate area of the presumed hardness limit zone. These measurements shall be carried out on the surface in question in one or more bands specified by agreement be- tween the parties and indicated on the drawing. For ea
15、ch, the results make it possible to plot the curve representing the hardness as a function of the distance from the surface. 4.4 Result of the measurement The curve or curves plotted make it possible to determine, for each band of the surface in question, the distance to the surface from the point w
16、here the hardness is equal to the hardness limit; this distance shall represent the effective depth of hardening after flame or induction hardening. 5 TEST REPORT The test report shall include the following particulars : a) the description of the part and its heat treatment; b) the area of the part
17、in which the tests were carried out; c) the effective depth of hardening after flame or in- duction hardening. Surface A A 1 7 d v a” a” I I ! I I FIGURE - Position of the hardness impressions 2 Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
